The present invention relates to a soft touch label comprising a coextruded film of a thermoplastic elastomer (TPE) and a polyolefin layer.
Current materials used for self-adhesive or heat-shrink film labels, for example polyethylene, polypropylene, polyethylene terephthalate and the like, have a plastic hard feel or touch. The packaging industry has shown an interest in the concept of xe2x80x9csoft touchxe2x80x9d films for use as self-adhesive or heat-shrink labels. While many thermoplastic elastomer materials have an inherent soft feel, films of these materials are difficult to form and process through printing and laminating equipment for the preparation of labels. Due to the high elongation characteristics of thermoplastic elastomers of more than 100%, printing on such films may result in print distortion and colors out of synchronization. Films of thermoplastic elastomers which are dimensionally stable under label making conditions would be desirable.
The present invention relates to film of thermoplastic elastomers which are dimensionally stable when used for manufacturing of pressure sensitive labels. It has now been found that dimensional stabilization of the films is achieved by coextrusion of the thermoplastic elastomer with a polyolefin material thus rendering said films suitable for label applications.
In particular the present invention relates to a label (1) comprising an adhesive layer (2) and a coextruded film (3) of
(a) an uppermost thermoplastic elastomer layer (4), selected from the group consisting of
blends of a thermoplastic polyolefin with a curable rubber selected from ethylene-propylene copolymer rubber, ethylene-propylene-diene rubber, butyl rubber, natural rubber, nitrile rubber, polyisoprene rubber, polychloroprene rubber, copolymer of C4-7 isomonoolefin and para-C1-8-alkyl styrene or its halogenated derivatives, polybutadiene rubber, styrene-butadiene rubber, or
styrene/conjugated diene/styrene block copolymer; and
(b) a polyolefin or polyester layer (5).
Preferred embodiments of the invention are as follows:
the coextruded film is printed on the outer surface of the polyolefin/polyester layer, on the outer surface of the thermoplastic elastomer layer, or both;
the coextruded film is laminated on its polyolefin/polyester side to an additional polyolefin sheet/base label, which may be printed;
lamination between the coextruded film and the polyolefin base label is effected by a layer of a laminating adhesive;
the additional polyolefin sheet is selected from polyethylene or a polypropylene sheet;
the adhesive layer is formed by a pressure sensitive adhesive;
the polyolefin of the coextruded sheet is selected from polyethylene or polypropylene;
the polyester of the coextruded sheet is an amorphous polyethylene terephthalate;
the label is applied to a substrate with paper being preferred;
the coextruded film is a heat-shrinkable uniaxially or biaxially heat-stretched film;
the coextruded film has a thickness of 40 xcexcm to 120 xcexcm;
the ratio thermoplastic elastomer layer to polyolefin layer of the coextruded sheet is from 1:9 to 1:1;
in the thermoplastic elastomer the rubber has been partially, fully or not cured.
By the term xe2x80x9cpressure-sensitivexe2x80x9d labels it is meant that no heat needs to be applied for effectively adhering the label with its adhesive side to an article.
By the term xe2x80x9csoftxe2x80x9d, xe2x80x9csoft-touchxe2x80x9d or xe2x80x9csoft thermoplastic elastomerxe2x80x9d there is meant the property of the uppermost layer of the coextruded sheet which originates from the thermoplastic elastomer having a Shore A hardness (ASTM D 2240) of from at least 35, preferably at least 40 to up to 80, preferably up to 70 and more preferably up to 60.